I feel your pain. In the future, stay clear of Dells. They use proprietatry bullshit that is impossible to upgrade without switching the mobo. That said,
The power saver message only means that the screen did not detect your pc and went into power saver mode. Usually, if it's your hard drive, you will get a "Disk Error" message Unplug POWER FIRST!! Look on the back of your tower at the top. You will see a fan. Behind that is your power supply(Dell loves to skimp here) Actually smell that area to see if you can detect any oder of melted plastic. If not, open up the side panel and find your hard drive cable. Looks like this:
If you have a floppy drive there will be 2 like this but the hard drive EIDE cable is the larger of the 2. Make sure it is plugged in firmly to the drive and the motherboard and while you're in there, check all power cords and basically anything that plugs into anything.
You did not say what operating system you are using but if you put the original cd(dvd) in the drive, it should give you the oportunity to repair or reinstall the o/s. If not, you have a definate hardware issue.
Finally, when you give up and throw your hands in the air,don't let the Geek Squad talk you into their bullshit software "upgrades".